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Blood Sciences

Blood Test Information

Alpha1 - antitrypsin (A1AT)
minimum sample volume required ~ 5ml

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Test Code: AAT

Tube type: SST

Reference range


Turnaround Time
1 day

Department: Biochemistry

Clinical Application
Alpha1-Antitrypsin is a glycoprotein consisting of a polypeptide chain to which 3 oligosaccharide chains are bounded (5400 daltons). It is synthesised in hepatocytes and is the most important proteinase inhibitor (Pi) in serum and plasma. It specifically inactivates serine proteases (e.g. trypsin, chymotrypsin, collagenase, leukocyte elastase, plasmin and thrombin), with which it reversibly forms an enzyme-indicator complex. Alpha1-Antitrypsin constitutes a major fraction of the electrophoresis alpha 1-globulin fraction. Alpha1-Antitrypsin is an important positive acute phase protein which is elevated concentrations in inflammatory processes (e.g. infectious and rheumatoid diseases), tissue necrosis, malignancy and traumas. Elevated levels often accompany inflammation of the liver parenchymal cells, although other acute phase protein levels are normal. Acute hereditary alpha1 -Antitrypsin deficiency is suspected in cases of neonatal hepatitis accompanied by progressive liver cirrhosis in early childhood. It is also suspected when severe pulmonary emphysema occurs in adults due to the prevalence of leukocyte elastase, which can lead to unrestrained proteolytic degradation of the pulmonary parenchymal cells. NOTE: Reference ranges depend on age of patient. If the concentration is below the median for age, the laboratory will forward the sample for phenotyping (see alpha1 -antitrypsin phenotype) if this has not already been done.

» MedlinePlus Medical Encyclopedia: Alpha-1 antitrypsin deficiency


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